Variable geometry turbine

Abstract

Variable geometry turbines having new configurations of vanes are disclosed. New methods for designating new configurations of vanes for geometry turbines having are also disclosed.

What is claimed is: 
     
         1 . A variable geometry turbine comprising:
 a turbine housing defining an inlet and an outlet;   a turbine wheel rotatably mounted in the turbine housing between the inlet and the outlet such that the turbine wheel can rotate about an axis;   a movable wall member mounted in the housing so as to be movable relative to the housing between at least a first position and a second position, the movable wall member partially defining an inlet passageway between the inlet and the turbine wheel, the inlet passageway being radially outboard of the turbine wheel, a dimension of the inlet passageway being dependent on the position of the movable wall member relative to the housing; and   a plurality of vanes extending across the inlet passageway, the vanes being circumferentially spaced;   wherein in cross section each of the vanes has an elongate shape extending from a leading edge which is closer to the inlet to a trailing edge which is closer to the turbine wheel and wherein a perpendicular thickness of the vane 5% along the length of the vane from the leading edge is at least 50% of the maximum perpendicular thickness of the vane; and   wherein an angular distribution of the vanes increases along the length of the vane from a first value at the leading edge to a maximum range of values and thereafter remains within the maximum range of values, wherein the maximum range of values varies by less than 0.5 degrees and wherein the angular distribution reaches the maximum range of values within 35% or less along the length of the vane from the leading edge.   
     
     
         2 . The variable geometry turbine of  claim 1  wherein a perpendicular thickness of the vane 95% along the length of the vane from the leading edge is at least 40% of the maximum perpendicular thickness of the vane. 
     
     
         3 . The variable geometry turbine of  claim 1  wherein the vanes and the turbine wheel are arranged such that a ratio of a radius of the trailing edge of each of the vanes to a radius of a leading edge of the turbine wheel is 1.2 or greater. 
     
     
         4 . The variable geometry turbine of  claim 1  wherein the vanes and the turbine wheel are arranged such that a ratio of a radius of the leading edge of each of the vanes to a radius of the trailing edge of each of the vanes is 1.2 or greater. 
     
     
         5 . The variable geometry turbine of  claim 1  wherein the vanes and the turbine wheel are arranged such that a ratio of a solidity ratio of the vanes in the range 1.1 to 1.3. 
     
     
         6 . The variable geometry turbine of  claim 1  wherein the leading edge of the vanes is provided with an elliptical end treatment having a ratio of the major axis to the minor axis of at least 1.5. 
     
     
         7 . A variable geometry turbine comprising:
 a turbine housing defining an inlet and an outlet;   a turbine wheel rotatably mounted in the turbine housing between the inlet and the outlet such that the turbine wheel can rotate about an axis;   a movable wall member mounted in the housing so as to be movable relative to the housing between at least a first position and a second position, the movable wall member partially defining an inlet passageway between the inlet and the turbine wheel, the inlet passageway being radially outboard of the turbine wheel, a dimension of the inlet passageway being dependent on the position of the movable wall member relative to the housing; and   a plurality of vanes extending across the inlet passageway, the vanes being circumferentially spaced;   wherein in cross section each of the vanes has an elongate shape extending from a leading edge which is closer to the inlet to a trailing edge which is closer to the turbine wheel and wherein a perpendicular thickness of the vane 95% along the length of the vane from the leading edge is at least 40% of the maximum perpendicular thickness of the vane; and   wherein the vanes and the turbine wheel are arranged such that a ratio of a radius of the trailing edge of each of the vanes to a radius of a leading edge of the turbine wheel is 1.2 or greater.   
     
     
         8 . The variable geometry turbine of  claim 7  wherein a perpendicular thickness of the vane 5% along the length of the vane from the leading edge is at least 50% of the maximum perpendicular thickness of the vane. 
     
     
         9 . The variable geometry turbine of  claim 7  wherein the vanes and the turbine wheel are arranged such that a ratio of a radius of the leading edge of each of the vanes to a radius of the trailing edge of each of the vanes is 1.2 or greater. 
     
     
         10 . The variable geometry turbine of  claim 7  wherein the vanes and the turbine wheel are arranged such that a ratio of a solidity ratio of the vanes in in the range 1.1 to 1.3. 
     
     
         11 . The variable geometry turbine of  claim 7  wherein the leading edge of the vanes is provided with an elliptical end treatment having a ratio of the major axis to the minor axis of at least 1.5. 
     
     
         12 . The variable geometry turbine of  claim 1  wherein in cross section each of the vanes has an elongate shape extending from a leading edge which is closer to the inlet to a trailing edge which is closer to the turbine wheel and wherein the vanes have a shape at least partially defined by the thickness distribution in Table 1 and the angular distribution in Table 2. 
     
     
         13 . The variable geometry turbine of  claim 12  wherein the actual thickness of the vanes, with an end treatment at each of the leading and trailing edges, is the thickness distribution in Table 13. 
     
     
         14 . The variable geometry turbine of  claim 1  wherein in cross section each of the vanes has an elongate shape extending from a leading edge which is closer to the inlet to a trailing edge which is closer to the turbine wheel and wherein the vanes have a shape defined by the curves in Tables 3, 4, 5 and 6 multiplied by a scale factor. 
     
     
         15 . A movable wall member for use in a variable geometry turbine;
 wherein the movable wall member is suitable for being movably mounted in a housing of the variable geometry turbine so as to partially define an inlet passageway of the turbine; and   wherein the movable wall member comprises a generally annular wall which supports a plurality of circumferentially spaced vanes, the cross section of each of the vanes having an elongate shape extending from a radially outer leading edge to a radially inner trailing edge and wherein a perpendicular thickness of the vane 5% along the length of the vane from the leading edge is at least 50% of the maximum perpendicular thickness of the vane; and   wherein an angular distribution of the vanes increases along the length of the vane from a first value at the leading edge to a maximum range of values and thereafter remains within the maximum range of values, wherein the maximum range of values varies by less than 0.5 degrees and wherein the angular distribution reaches the maximum range of values within 35% or less along the length of the vane from the leading edge.   
     
     
         16 . A method for designing the vanes for a variable geometry turbine, the method comprising:
 selecting a thickness distribution; and   applying an edge treatment to each of the leading edge and trailing edge, the edge treatment for the leading edge being elliptical in cross-section, having a ratio between the minor and major lengths of 1.5 or more;   such that a perpendicular thickness of the resultant vane 5% along the length of the vane from the leading edge is at least 50% of the maximum perpendicular thickness of the vane.   
     
     
         17 . The method of  claim 16  further comprising:
 selecting a radius of the trailing edge of the vanes such that a ratio of the radius of the trailing edge of the vanes to a radius of a leading edge of the turbine wheel is within the range 1.2 to 1.25. 
 
     
     
         18 . The method of  claim 16  further comprising:
 selecting an outer diameter of the vane leading edge such that the ratio of the radius of the leading edge of the vanes to the radius of the trailing edge of the vanes is 1.2. 
 
     
     
         19 . The method of  claim 16 , wherein the selection of the thickness distribution and the application of the edge treatment to each of the leading edge and trailing edge is such that a perpendicular thickness of the resultant vane 95% along the length of the vane from the leading edge is at least 40% of the maximum perpendicular thickness of the vane. 
     
     
         20 . A method for designing the vanes for a variable geometry turbine having a turbine wheel, the method comprising:
 selecting a radius of the trailing edge of the vanes such that a ratio of the radius of the trailing edge of the vanes to a radius of a leading edge of the turbine wheel is within the range 1.2 to 1.25; and   selecting an outer diameter of the vane leading edge such that the ratio of the radius of the leading edge of the vanes to the radius of the trailing edge of the vanes is 1.2.